1. Field of the Invention
This tool is useful in removing the common steel frame type casement windows, for instance for replacement with more modern window units.
2. Description of the Prior Art
In prior times, a steel frame type of casement window was commonly used in buildings. This window unit generally comprised a steel frame containing glass window panels, one or more of which often had its own steel frame so that it could be opened and closed with a crank or other means.
These generally rectangular casement windows are usually permanently built into the wall opening with the main frame of the casement window being contained at the interior side of the wall by another steel frame of slightly smaller rectangular proportion that is embedded within the building wall. From the interior side, these casement windows are generally contained by the plaster interior sill and wall sides of the window opening. In replacing these casement type windows with windows having more advantageous features for easier cleaning, lower heat loss, etc., it thus is nearly always necessary to force the main frame of the window outward past the frame embedded in the wall. The embedded frame generally has an inside clearance that is slightly smaller than the outside dimensions of the portion of the main frame of the casement window which is held by the embedded frame.
Therefore it is necessary to exert considerable force on the casement window main frame, to force it outward past the embedded frame. The main frame of the casement window is to some extent distorted from this forcing of a portion of the main frame past the embedded frame. Generally the negative clearance between the two is relatively small, the relative proportions having been disigned merely to ensure containing the casement window against the forces usually encountered by a window unit. Thus an elastic distortion is usually sufficient for springing the casement unit outward past the embedded frame that contains it.
The tools that are generally used in this operation include a variety of the most common type of tool. This includes the hammer, chisel, screwdriver, prying bar, etc. These typically result in more than elastic distortion of the casement window, in damage to the interior wall and sill portions adjacent the casement window, and the exterior portions of the exterior wall and sill are also frequently damaged. Use of these basic tools usually requires considerable exertion and repeated attempts to gain the necessary mechanical advantage to force the casement unit outward past the embedded frame.
Use of such tools generally requires, or at least results in, considerable breakage of the glass panels in the casement window unit being removed. This is potentially quite dangerous for the workmen removing the window, and further results in broken glass at the job site.